MICROCOCCI 211 



Micrococcus Versicolor. Small cocci, arranged in small groups or 

 in the form of diplococci. They are very frequent in the air. The 

 cultures present an irregular form and yellowish-green colour. On 

 gelatine they exhibit a mother-of-pearl like iridescence, and cause 

 fermentation in grape sugar media. 



(b.) NON-CHROMOGENIC. 



Micrococcus Candicans. Round medium-sized cocci, best known 

 by their growth in gelatine stab cultures, in which they form a nail-like 

 growth with a porcelain white shiny head. 



Micrococcus Concentricus. Small cocci, arranged like bunches of 

 grapes (Staphylococci), characterised by the zonary growth of the 

 colonies on gelatine plates and in stab cultures. The colonies vary in 

 colour from white to a bluish-grey, and are indented on the surface. 



Micrococcus Rosettaceus. Medium-sized cocci. The growth is 

 frequently superficial in rosette-formed masses, with irregular edges of a 

 greyish colour, the central portion varying from dark grey to brown. 



Micrococcus Aquatilis. Round light grey colonies with a mother- 

 of-pearl lustre, the edges appearing indented. Under a low power the 

 colonies resemble a berry in shape. 



2. Nutrient Gelatine is Liquefied, 

 (a.) CHROMOGENIC. 



Micrococcus Cremoides. Small cocci, arranged in bunches, and 

 forming a cream-coloured pigment. In the commencement on gelatine 

 yellowish-white to brownish-green granular circular colonies develop ; 

 later, the discs appear fixed, and lie in a liquefied depression. 



Micrococcus Agilis. Strongly motile coccus, possessing flagella ; 

 grows on the different media, forming a rose-coloured pigment. 

 Gelatine media are liquefied slowly. 



Sarcina Lutea (Yellow Sarcina). Strongly aerobic cocci, arranged 

 in the so-called bale-like forms. On gelatine plates, round, slightly 

 granular yellow colonies develop. 



In Stab Cultures a strong surface growth. The cultures form a citron 

 yellow pigment. The gelatine is liquefied very slowly, and the citron 

 yellow growth falls to the bottom of the tube, while the upper portion 

 of the medium remains clear. 



Besides the yellow sarcina, there are white, orange, and red sarcinae, 

 which are only distinguished from the above-mentioned yellow form by 

 the different colours of the pigment produced. These sarcinae are all 

 found in the air. 



